System Resource (IRQ, DMA, I/O, COM) Conservation and Optimization
This section describes several ways that you can conserve or free up your valuable and limited system resources. Note that there are two commonly-used definitions of the term "system resources". Here, I am talking about interrupt request lines (IRQs), direct memory access channels (DMAs), I/O addresses and COM ports. The other use of the term refers to the special system memory areas within the Windows operating system; optimizations for these are discussed here.
Freeing up system resources can be extremely important if you are having problems adding new hardware into your PC. Problems with peripherals can usually be traced to incorrect configuration, which in turn usually means a resource conflict. These can sometimes be hard to resolve in part because of a perceived lack of free IRQs and other resources. These tips may help you to free up a resource that is being inefficiently utilized.
Free Up a Serial (COM) Port by Using A PS/2-Style Mouse
There are two main types of mice used on modern PCs. The first is the serial mouse, which as the name implies uses a serial (COM) port on the PC. The second is the PS/2-style mouse which uses a dedicated port and its own interrupt setting, separate from the COM ports.
One problem that many users run into is resource conflicts related to the serial ports, or the two IRQ lines that they use. You can have up to four COM ports in a system, but by default they share only two IRQs, IRQ3 and IRQ4. This can lead to numerous problems, and they can be hard to resolve because many modems and other devices can only use the low-numbered IRQs (2 through 7). However, the PS/2-style mouse uses IRQ12, which on many systems is unused. So going to a PS/2-style mouse from a serial mouse may solve a lot of problems.
Many PCs support PS/2-style mice, but in some cases the support is not implemented or the manufacturer puts a serial mouse on the system anyway due to laziness or cheapness. Here's what you need to do if you want to move to a PS/2 mouse:
Determine What You Are Using Now: This is pretty easy to do; the simplest way is to check the connection to the PC; if the mouse is plugged into a small, round connector on the PC, you are already using a PS/2-style mouse (most of the larger retail brands use them). If the mouse is going to a 9-pin or 25-pin D-shaped connector, it is a serial mouse. You can also use the Windows 95 Device Manager or the Windows 3.x Setup program to see what sort of mouse is installed.
Determine PS/2 Support: If you are currently using a serial mouse, the next thing you need to do is find out if your system supports a PS/2-style mouse. Check the back of the PC again; if you see a small, round, 6-pin connector (don't confuse it with the keyboard connector; there may be two similar connectors on some PCs) then you probably have PS/2 support. If you don't see the connector, you may still be able to use the PS/2 mouse. Some motherboard have a header for the PS/2 mouse but some manufacturers don't install the connector on the case for some reason. The reliable way to check if this situation applies to you is to check in your BIOS setup program for BIOS settings related to the PS/2 mouse. If you see them, that means your motherboard supports the PS/2 mouse. You should inspect the motherboard for the PS/2 header, and then contact the vendor or manufacturer about a PS/2 mouse connector to attach to it. Then install it, ensure that it is enabled in the BIOS setup, and you are all set. You may want to refer to this procedure, which describes how to install the internal PS/2 mouse port on AT-based systems without an integrated port.
Enable PS/2 Mouse Support: Check the BIOS setup program for any settings that might exist to enable or disable PS/2 mouse support. Ensure that the port is enabled.
Obtain a PS/2 Mouse: You will need a PS/2 style mouse. There are some mice that can function as either PS/2 or serial mice, but most are only one or the other; see here for more on this. If yours can do either (called a "combo" mouse) then you should be able to use your serial mouse in the PS/2 port, with an inexpensive adapter. Otherwise, you will need to buy a PS/2 mouse. If possible, buy one from a place that allows returns, in case there is a problem and you have to go back to using the serial mouse.
Install the PS/2 Mouse: This is of course a simple matter of plugging it into the PS/2 mouse port.
Switch Mouse Drivers: If you are using Windows 95 with Plug and Play, your PC should detect the hardware change and adjust the drivers for you. Otherwise, you will have to manually change from the serial mouse driver to a PS/2 driver.
Disable the COM Port in the System BIOS Setup: You must remember to disable the COM port using the appropriate BIOS setting in your BIOS setup program, in order to actually accomplish your goal of freeing up the COM port and the IRQ it uses. You'll want to do this if, for example, you want to install an internal modem that uses the same COM port number. In some cases you may not want to do this, for example if you still want to use the built-in COM port for a different external device.
Warning: If you had any devices that were using IRQ12 before you made this change, you may now have a resource conflict, since the mouse uses IRQ12. You will have to change the other device to use another IRQ. If it is a PCI device then you may be able to solve the problem by changing which PCI slot it is using.
Free Up IRQ12 by Disabling the Built-in PS/2 Mouse Port and/or Moving to a Serial Mouse
Many newer PCs come with an integrated PS/2-style mouse port. Using this port allows you to conserve a serial port and serial port IRQ that would otherwise be used for your serial mouse. However, some people do not use their PS/2 mouse port; the most usual reason is upgrading from a previous system that didn't have one and not wanting to purchase a new PS/2 mouse. Also, in some rare cases IRQ12 might be needed more than the serial port's IRQ, so you may want to switch from PS/2 to a serial mouse.
Before you do anything, verify what type of mouse you are currently using. This is pretty easy to do; the simplest way is to check the connection to the PC; if the mouse is plugging into a small, round connector on the PC, you are already using a PS/2-style mouse (most of the larger retail brands use them). If the mouse is going to a 9-pin or 25-pin D-shaped connector, it is a serial mouse. You can also use the Windows 95 Device Manager or the Windows 3.x Setup program to see what sort of mouse is installed.
If you are already using a serial mouse on a system that includes a PS/2 mouse port, disabling the port is easy and will free up IRQ12. Go into the BIOS setup program and look for a BIOS parameter called something like "PS/2 Mouse Enable". Disable the parameter and the PS/2 mouse port will "disappear" from the operating system and its IRQ will be freed up as well.
If you are currently using a PS/2 mouse and want to move to a serial mouse, here's what you will have to do:
Disable PS/2 Mouse Support: Check the BIOS setup program for any settings that might exist to enable or disable PS/2 mouse support. Usually this will be called something like "PS/2 Mouse Enable". Disable the setting.
Obtain a Serial Mouse: You will need a serial mouse. There are some mice that can function as either PS/2 or serial mice, but most are only one or the other; see here for more on this. If yours can do either (called a "combo" mouse) then you should be able to use your PS/2 mouse in a serial port, with an inexpensive adapter. Otherwise, you will need to buy a serial mouse. If possible, buy one from a place that allows returns, in case there is a problem and you have to go back to using the PS/2 mouse.
Install the Serial Mouse: Install the mouse into the serial port. Normally, serial port 1 is used for the mouse; if you have another device using it already (such as a modem) you can use COM2 but this is non-standard.
Switch Mouse Drivers: If you are using Windows 95 with Plug and Play, your PC should detect the hardware change and adjust the drivers for you. Otherwise, you will have to manually change from the PS/2 mouse driver to a serial mouse driver.
Warning: If you had any devices that were using COM ports before you made this change, you may theoretically now have a resource conflict, since the mouse will be using one of the ports. In particular, if you already have two COM ports in use, I do not recommend eliminating the PS/2 mouse, as you will have a problem finding enough low-numbered (2 to 7) IRQs for all the serial devices.
Avoid Resource Conflicts By Using IRQ2/IRQ9
Many resource conflicts are tied to multiple devices fighting over the same IRQ lines. This is particularly a problem with the lower-numbered IRQ lines, from IRQ 0 to IRQ 7. Of these eight IRQs, 0 and 1 are reserved by the system, 3 and 4 are used by serial (COM) ports, 5 is normally used by the sound card, 6 is used by the floppy drive and 7 is normally reserved for the printer port. This leaves just IRQ 2, and many people are afraid to use it because of its special role as the interrupt cascade; it connects the high-numbered IRQs to the system. This confusing subject is described in detail here.
In fact, IRQ2 can be used. When the AT PC was designed and the 8 extra IRQ lines were installed, what used to be IRQ2 was rerouted to use the IRQ9 line. This means that any peripheral that is set to use IRQ2 will be seen by the system as using IRQ 9. As long as you don't set any devices to use IRQ 9, therefore, you can use IRQ 2. Just set the device to IRQ 2, and configure the software (driver, communications program, etc.) to use IRQ 9.
This can be extremely useful on a system with two COM ports, a printer, a modem and a sound card. Set the modem to use IRQ 2 and it will show up as IRQ 9 to the software. Most modems have a jumper that will let you do this.
Free Up an ISA/VLB/PCI Expansion Card Slot
Many modern PCs have relatively few expansion slots; some have as few as three. Many of the smaller boxes that have few slots do not need as many in the first place because they have built-in components such as video cards; even still, expansion and adding peripherals can be difficult when there are few slots in the system. Even PCs with a number of slots can run out when you start adding a number of devices. Furthermore, modern PCs typically have a limited number of PCI and ISA slots, and depending on how you use your system, you may find that you have plenty of one type but not nearly enough of the other.
Here are a few ideas for freeing up an expansion slot, if this is an issue for you:
Free Up Slots Blocked by Port Connectors: Many PCs run out of expansion slots for a silly reason: the slots are being wasted because they are blocked by the connectors for the serial and parallel ports. While ATX form factor motherboards have these ports built into the motherboard itself, the conventional AT or baby-AT style motherboard uses ports that connect to the motherboard with a ribbon cable. These come with the motherboard installed into a piece of metal that fits into an expansion slot, to make assembling the PC faster (and cheaper). However, most modern cases have punch-out holes in the back of the case itself for these connectors. By unscrewing the connectors from the slot insert and screwing them into the holes in the back of the case, you can remove the inserts and free up a potentially wasted expansion slot--sometimes even two.
Remove Unnecessary Devices: You'd be surprised how often I find devices in PCs that were installed a long time ago but are no longer being used. Removing these unneeded cards will of course free up the slots they are using, if this is an option for you.
Make Optimal Use of VESA Local Bus (VLB) Slots: VLB slots are physically an extension of the ISA slot; the VLB slot is an ISA slot with two extra connectors on the end. ISA slots will therefore work in a VLB slot; if your ISA slots are all filled and there is a VLB slot free, you can use it. However, there are usually very few VLB slots on a VLB motherboard, so only put ISA cards there if you are out of ISA slots.
Optimize Shared Slots: Many PCI motherboards have a "shared" PCI/ISA slot. This is a slot that can either hold an ISA or a PCI card, but not both. It is possible because of how PCI cards are mounted "upside-down" to their slot inserts compared to how ISA cards are. If you have a board like this and you are out of ISA slots but have a free PCI slot, see if you have a PCI device in the shared slot, and if so, move it to the free PCI slot. Similarly if you are out of PCI slots but have a free ISA slot and an ISA card in the shared position.
Tip: IRQ conflicts can sometimes result from changing the slot a PCI card uses, due to how these devices are assigned IRQs.
Free Up an IRQ by Combining IDE channels and Disabling Unused Ones
Most newer motherboards come with two IDE/ATA channel controllers built in, for using IDE hard disks, CD-ROMs and similar devices. Each of these controllers uses an IRQ; the normal allocations are IRQ14 for the primary IDE controller, and IRQ15 for the secondary channel. In many cases, it is possible to recover at least one of these IRQs if you need them for other devices such as a SCSI host adapter, network card or tape accelerator card.
Here are some ideas that you can use:
Disable Unused Motherboard IDE Channels: If you are only using the primary IDE channel on a system with a motherboard that contains two built-in controllers (and most do), then you should disable the secondary controller to free up the resources it uses. This is easy: simply go into the BIOS setup and look for the settings that control the IDE controllers. These are usually found in the "Integrated Peripherals" grouping (and not where the hard disk parameters are entered, mind you.) Disable the secondary IDE controller; how exactly you do this depends on how the settings are programmed on your PC.
Disable All IDE If Using SCSI Only: If you are using only SCSI devices and no IDE at all, disable all the IDE controllers on the system. This is done in a similar way to disabling the secondary controller, as described immediately above.
Disable Unused IDE Ports on Sound Cards: Many sound cards today come with integrated IDE ports on them, intended for supporting CD-ROM drives as part of multimedia kits. These often are set up to establish themselves as tertiary IDE controllers, using IRQ11 or IRQ12. Most people don't use them because their motherboards have two IDE controllers already. If you aren't using yours, disable the IDE controller using whatever means the sound card provides: usually this is either a jumper on the sound card, or a setting in a special setup program.
Rearrange IDE Channel Usage: Each IDE channel can handle two hard disks, CD-ROM drives or other devices. For optimal performance, though, many people (including myself) recommend using only one device per channel if you have two IDE devices. If on the other hand saving an IRQ is more of a priority for you than optimal performance (and the difference in performance in some cases isn't really large) then you may want to rearrange your setup and put both devices on the primary channel, and then disable the secondary channel as above. This section in the Reference Guide discusses IDE device configuration and lays out all the options.
Use an Add-in 16-Bit Card I/O Card for Multiple Serial Ports
If you need to run three, four or more serial-port devices on your PC, you will have problems finding enough IRQ lines for them all. One option that is available to you is to make use of an add-in I/O controller. If you get one that has a 16-bit ISA connector, it should allow you to use the higher-numbered IRQs--9 through 15--for the COM ports. The built-in COM ports on the motherboard usually only allow you to use the low-numbered IRQs, usually only 3, 4 or 5.
If you use one of these add-in cards, be sure to disable the integrated COM ports in the BIOS setup; otherwise the new and old ports will conflict with each other. Make sure you purchase one that supports the higher-numbered IRQs.
Miscellaneous Improvements
This section contains a few optimizations that don't fit neatly into any of the other categories
Eliminate Accidentally Turning Off Turbo Mode on Turbo PCs
I occasionally run into an older PC that suddenly drops in performance dramatically; suddenly, one day, the system is running at a fraction of its previous speed. There are many possible causes for this problem, but one annoying cause is accidentally disabling turbo mode on a PC that uses it. Many older 286, 386 and 486 machines have a turbo button on them. When enabled, "turbo" actually allows the system to run at its intended full speed; when disabled, the PC slows down.
Today, newer PCs don't generally bother with this; some cases still have the button but it won't generally do anything. Even older PCs rarely have any use for this feature. You can disabled the turbo button if you aren't using it, or if you keep disabling turbo by accident, fairly easily:
Open the PC: Power down and then open up the PC.
Locate the Turbo Pin Connector: Find the connector on the motherboard that controls the turbo setting. Two easy ways to do this are to either check your system or motherboard documentation, or follow the two wires from the turbo button on the cases, to where they connect to the motherboard.
Pull the Connector From the Motherboard: Simply disconnect the wires from the pins that they are connected to. If the pins on the motherboard aren't labeled, and if you don't have the motherboard manual, make a note on a piece of paper indicating which pins the wires were connected to, in case you ever want to reconnect the button.
Test the System: Carefully, power the system up. Then, check the turbo LED to see if it is on, and check the system speed. If the LED is on and the system speed is normal (fast), then you are all done. If the system speed is slow and the LED is off, then your motherboard probably requires the turbo switch to be shorted to work properly. Turn the PC off, and use a jumper to connect the two pins on the motherboard for the turbo switch together. Then turn it on and everything should work. If it still doesn't, then you should undo the changes that you made and just be more careful with the turbo button. Taping over it should work too.
Improve Floppy Disk Read and Write Speed
Floppy drives have essentially remained unchanged for around 10 years, excluding the poorly-accepted 2.88 MB version. They are generally slow devices, but there is one simple way I have found to speed up their performance: use them under Windows 95. Windows 95 uses high-performance 32-bit floppy disk drivers, which are substantially faster than the routines used by DOS. Even if you open a DOS prompt window under Windows 95 and use your DOS floppy-disk programs there, you will see a substantial performance improvement over working with the floppy in plain DOS.
Speed Up Parallel Port Operations (Including Printing)
Your PC's parallel port is used primarily for printing in most cases; in the last few years, however, a large number of other devices have come on the market which use the parallel port as the interface to the system. The main reason I believe is that the parallel port is so standard: every PC has one.
There originally was only one type of parallel port, but now there are several different types, which were invented to improve performance when printing or using the port for data transfer and similar activities. By default, many PCs come with the parallel port at its slowest setting. You can improve performance by changing the parallel port mode, using this BIOS setting.
Speed Up Tasks by Using the Third (Middle) Mouse Button
If you have a mouse with three buttons, you should consider using software to program the middle button to perform a useful function. The most common one is a double-click; on my Logitech mouse, when I want to double-click an icon to launch it, or the corner of a window to close it, I need only press the middle button once. This sounds like no big deal, but it's a real time and hassle saver, to the point where I have trouble even using a two-button mouse now.
To set this up, you will need a three-button mouse from a reputable manufacturer (like Logitech). The mouse should come with a driver that will allow you to program the third button.
Booting CD Rom System Cleanup CPU & Motherboard Hard Disk Sound Card
Modem Monitor Mouse System Enhancements Windows Shell
Some part of this document is taken from www.tweak3d.net and www.pcguide.com.
